In short: Choose an FRP trench cover by where it sits and what will cross it. EN 124 load classes go from A15 (pedestrians only) to F900 (aircraft pavements). EN 124-5, the part for composite covers, covers classes A15 to D400. Use B125 for footpaths and car parks, C250 for curbside areas and D400 for roads. When in doubt, choose the stronger class.
Which load class do you need?
EN 124 sets the load class by where the cover sits. For trench runs the usual choices are B125 (footways, pedestrian areas, car parks), C250 (curbside channels) and D400 (road carriageways); A15 is for pedestrian and cycle areas only. The full EN 124 table, from A15 to F900 with test loads, is in our FRP manhole covers vs cast iron guide.
EN 124-5 (composite materials) covers classes A15 to D400 for single-piece, machine-made products. For E600 or F900 duty, or for hand-laid-up covers, check what the supplier actually certifies.
How trench covers differ from manhole covers
A manhole cover closes one opening in a frame. A trench cover closes a long, narrow run, so it is many covers laid end to end over a ledge or angle frame. That changes what you need to specify. The material choice (FRP vs cast iron, theft and weight) is covered in our FRP manhole covers vs cast iron guide; this page deals with the run itself.
Trench cover run vs single manhole cover
| Point | Single manhole cover | Trench cover run |
|---|---|---|
| Shape | One round or square opening | Long, narrow run of rectangular covers |
| Main dimension | Clear opening | Clear trench width (the span of each cover) |
| Load path | Cover seated all round in a frame | Cover spans across the trench, seated on two ledges |
| Joints | None | Cover-to-cover joints along the run |
| Access pattern | Opened occasionally | Covers lifted often for cable pulling or cleaning |
| Layout items | Frame, lock, hinge | Corners, tees, end stops, cut covers around posts |
Drainage channel or cable trench: which standard?
Check what the trench is for before naming a standard. EN 124 covers gully tops and manhole tops, and it excludes the gratings and covers of prefabricated drainage channels. Those are covered by EN 1433, which tests the channel and its grating as one system and uses the same load class names, A15 to F900. For a cable or service trench, the project usually names EN 124 load classes for the covers. Confirm with the designer which standard the specification means, and ask for test evidence to that standard.
Sizing covers for a long run
- Cover length. Shorter covers are lighter to lift but add joints. Choose a length that one or two people can lift under your site’s manual handling rules, and state it.
- Span direction. The cover spans across the trench. Its stiffness must be checked across the clear width, plus the ledge bearing on each side.
- Joints. Keep joints small and even, and make sure each cover sits on its own ledge without bridging onto the next.
- Layout drawing. Mark corners, tees, ends and any covers cut around posts. Number the covers so they go back in the same place.
- Lifting. Specify lifting slots or keys that will not trap water or dirt. For covers lifted often, ask for a design that cannot be refitted upside down.
For cable trenches at substations and EV charging sites, also tell us the cable pulling routine and whether covers must be lifted without tools. See FRP at EV charging stations.
What else should you specify?
- Clear opening and overall size: plus the frame type, or "cover only" for existing frames.
- Load class and standard: for example "EN 124-5 C250", with test certificates.
- Surface: anti-slip grit finish. See FRP grating surface options.
- Locking and lifting: locks, hinges or lifting keyholes as needed.
- Solid or open: solid covers, or grating panels where ventilation or drainage is needed.
How should covers be installed?
- Level seating: covers must sit fully on the frame or ledge, with no rocking.
- Frame bedding: set the frame into the surrounding pavement as the frame maker instructs.
- Gaps: keep gaps between covers small and even.
- Inspection: check regularly for cracks, wear and loose locks.
How FIBROVX can help
Send us the trench widths, lengths, load class and location, and we will quote covers, with frames if required. Request a quote. CIF by default, FOB on request.
Common mistakes
- Choosing B125 where vehicles may stray: use C250 or D400.
- Assuming every FRP cover meets EN 124: ask for test certificates.
- Covers rocking on uneven seats: this causes breakage and trip hazards.
- No anti-slip finish in wet areas: specify grit.
Key terms
- EN 124: the European standard for gully tops and manhole tops.
- Test load: the load applied in the type test for each class.
- Clear opening: the open area under the cover.
- Frame: the seat that the cover sits in.
FAQ
Can FRP covers take road traffic? Composite covers certified to EN 124-5 class D400 are designed for road carriageways.
What load class is a footpath? Usually B125. Use A15 only where vehicles cannot reach.
Does EN 124 cover composite trench covers? Yes. EN 124-5 covers composite gully and manhole tops in classes A15 to D400.
What if I am unsure of the class? Choose the stronger class.
Related guides
- FRP manhole covers vs cast iron
- FRP at EV charging stations
- FRP grating guide
- FRP telecom infrastructure
- Request a quote
Sources
- EN 124-1:2015 and EN 124-5:2015, Gully tops and manhole tops (BSI/CEN): https://knowledge.bsigroup.com/products/gully-tops-and-manhole-tops-for-vehicular-and-pedestrian-areas-gully-tops-and-manhole-tops-made-of-composite-materials
- A UK access cover manufacturer, EN 124 load classes guide
- CEN, EN 1433 Drainage channels for vehicular and pedestrian areas (catalog), https://standards.iteh.ai/catalog/standards/cen/9941554f-1875-46dc-80e1-ff9fb8851cb0/en-1433-2002